/* =====================================================================
   RHCES /learn: article and index layout
   Sits on top of style.css + theme.css (CAD theme). Every colour reads the
   theme.css drafting tokens (--cad-*), so light/dark follow html[data-theme].
   Fallbacks are the light-theme values, used only if theme.css is missing.
   ===================================================================== */

/* ── Figure palette (contract shared with the SVG diagram makers) ───── */
:root,
html[data-theme="light"] {
  --fig-bg: #ffffff;
  --fig-ink: #1b2225;
  --fig-muted: #5b6670;
  --fig-line: #9aa5ad;
  --fig-accent: #0d6c87;
  --fig-concrete: #d9dde0;
  --fig-soil: #d8c3a0;
  --fig-steel: #b0413e;
  --fig-water: #3b82c4;
  --fig-pass: #1f8a4c;
  --fig-fail: #c0392b;
  --fig-warn: #c98a00;
}
html[data-theme="dark"] {
  --fig-bg: #171c1e;
  --fig-ink: #e2e7e6;
  --fig-muted: #a2adaf;
  --fig-line: #56636a;
  --fig-accent: #5db8d3;
  --fig-concrete: #3b4448;
  --fig-soil: #6e5b3f;
  --fig-steel: #e8817a;
  --fig-water: #6aaee8;
  --fig-pass: #6cc08b;
  --fig-fail: #ef8a7d;
  --fig-warn: #e6b34a;
}

/* ── Page frame ─────────────────────────────────────────────────────── */
.learn-page .navbar {
  background: var(--cad-ground, #E3E7E6);
  border-bottom-color: var(--cad-rule, #C2CAC9);
}

.learn-skip {
  position: absolute; left: -9999px; top: 0; z-index: 2000;
  padding: 10px 16px; border-radius: 3px;
  background: var(--cad-accent, #0D6C87); color: var(--cad-accent-ink, #fff);
  font-weight: 600;
}
.learn-skip:focus { left: 12px; top: 12px; }

.learn-main {
  padding: calc(var(--nav-h, 72px) + env(safe-area-inset-top, 0px) + 28px) 0 72px;
  background: var(--cad-ground, #E3E7E6);
  color: var(--cad-ink, #1B2225);
}

.learn-wrap {
  max-width: 828px;              /* 780 px reading column + 2 x 24 px gutter */
  margin: 0 auto;
  padding: 0 24px;
}

/* ── Breadcrumb ─────────────────────────────────────────────────────── */
.learn-breadcrumb { margin: 0 0 14px; font-size: .875rem; line-height: 1.4; }
.learn-breadcrumb ol {
  list-style: none; margin: 0; padding: 0;
  display: flex; flex-wrap: nowrap; align-items: baseline; gap: .5rem;
  color: var(--cad-ink-2, #4D595D);
  min-width: 0;
}
.learn-breadcrumb li { flex: none; white-space: nowrap; }
.learn-breadcrumb li + li::before {
  content: "/"; margin-right: .5rem; color: var(--cad-ink-3, #7A8588);
}
.learn-breadcrumb li:last-child {
  flex: 0 1 auto; min-width: 0; overflow: hidden; text-overflow: ellipsis;
}
.learn-breadcrumb a { color: var(--cad-accent, #0D6C87); }
.learn-breadcrumb a:hover { text-decoration: underline; text-underline-offset: 2px; }

/* ── Sheet (the article "paper") ────────────────────────────────────── */
.learn-sheet {
  background: var(--cad-panel, #F5F7F6);
  border: 1px solid var(--cad-rule, #C2CAC9);
  border-radius: 4px;
  padding: 40px 48px 44px;
}

.learn-head {
  margin: 0 0 1.9rem;
  padding: 0 0 1.25rem;
  border-bottom: 1px solid var(--cad-rule, #C2CAC9);
}
.learn-kicker {
  margin: 0 0 .55rem;
  font-size: .78rem; font-weight: 700; letter-spacing: .09em; text-transform: uppercase;
  color: var(--cad-accent, #0D6C87);
}
.learn-sheet h1,
.learn-index-head h1 {
  margin: 0 0 .7rem;
  font-family: var(--font-display, "Barlow Condensed", "Arial Narrow", sans-serif);
  font-size: clamp(1.85rem, 1.25rem + 2.4vw, 2.6rem);
  font-weight: 700;
  line-height: 1.12;
  letter-spacing: -.003em;
  color: var(--cad-ink, #1B2225);
  text-wrap: balance;
}
.learn-meta {
  margin: 0;
  display: flex; flex-wrap: wrap; align-items: baseline; gap: .2rem .55rem;
  font-size: .92rem; line-height: 1.5;
  color: var(--cad-ink-2, #4D595D);
}
.learn-meta a { color: var(--cad-ink, #1B2225); font-weight: 600; }
.learn-meta a:hover { color: var(--cad-accent, #0D6C87); }
.learn-meta-sep { color: var(--cad-ink-3, #7A8588); }

/* ── Article body typography ────────────────────────────────────────── */
.learn-body {
  font-size: 1.0625rem;
  line-height: 1.75;
  color: var(--cad-ink, #1B2225);
  overflow-wrap: break-word;
}
.learn-body p { margin: 0 0 1.1em; }
.learn-body h2 {
  margin: 2.3em 0 .7em;
  font-family: var(--font-display, "Barlow Condensed", "Arial Narrow", sans-serif);
  font-size: 1.62rem; font-weight: 700; line-height: 1.2;
  color: var(--cad-ink, #1B2225);
  scroll-margin-top: calc(var(--nav-h, 72px) + 16px);
}
.learn-body h2::before {
  content: ""; display: block; width: 36px; height: 3px; margin-bottom: .5em;
  background: var(--cad-accent, #0D6C87); border-radius: 2px;
}
.learn-body h3 {
  margin: 1.8em 0 .6em;
  font-size: 1.2rem; font-weight: 700; line-height: 1.3;
  color: var(--cad-ink, #1B2225);
  scroll-margin-top: calc(var(--nav-h, 72px) + 16px);
}
.learn-body h4 { margin: 1.5em 0 .5em; font-size: 1.05rem; font-weight: 700; }
.learn-body > :first-child { margin-top: 0; }

.learn-body a {
  color: var(--cad-accent, #0D6C87);
  text-decoration: underline; text-decoration-thickness: 1px; text-underline-offset: 3px;
}
.learn-body a:hover { text-decoration-thickness: 2px; }
.learn-body strong { font-weight: 700; color: var(--cad-ink, #1B2225); }
.learn-body em { font-style: italic; }

.learn-body ul,
.learn-body ol { margin: 0 0 1.2em; padding-left: 1.45em; }
.learn-body ul { list-style: disc; }
.learn-body ol { list-style: decimal; }
.learn-body li { margin: .4em 0; padding-left: .25em; }
.learn-body li::marker { color: var(--cad-accent, #0D6C87); }
.learn-body ol > li::marker { font-weight: 700; }
.learn-body li > ul,
.learn-body li > ol { margin: .3em 0 .4em; }

.learn-body code {
  font-family: var(--font-mono, "IBM Plex Mono", ui-monospace, Consolas, monospace);
  font-size: .9em;
  padding: .06em .35em;
  border-radius: 3px;
  background: var(--cad-stage, #EEF1F0);
  border: 1px solid var(--cad-rule-2, #D9DFDE);
}

.learn-body hr {
  border: 0; border-top: 1px solid var(--cad-rule, #C2CAC9);
  margin: 2.4em 0;
}

/* Formula box: every > blockquote in the drafts is a worked calculation */
.learn-body blockquote {
  margin: 1.35em 0 1.5em;
  padding: .85em 1.15em;
  background: var(--cad-stage, #EEF1F0);
  border: 1px solid var(--cad-rule-2, #D9DFDE);
  border-left: 3px solid var(--cad-accent, #0D6C87);
  border-radius: 0 4px 4px 0;
  font-family: var(--font-mono, "IBM Plex Mono", ui-monospace, Consolas, monospace);
  font-size: .94rem;
  line-height: 1.75;
  color: var(--cad-ink, #1B2225);
  overflow-x: auto;
}
.learn-body blockquote p { margin: 0; }
.learn-body blockquote p + p { margin-top: .6em; }
.learn-body blockquote strong { color: var(--cad-ink, #1B2225); }

/* Tables (wrapper scrolls sideways on phones) */
.learn-table {
  margin: 1.5em 0 1.7em;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  border: 1px solid var(--cad-rule, #C2CAC9);
  border-radius: 4px;
  background: var(--cad-panel, #F5F7F6);
}
.learn-table:focus-visible { outline: 2px solid var(--cad-accent, #0D6C87); outline-offset: 2px; }
.learn-table table {
  width: 100%;
  border-collapse: collapse;
  font-size: .95rem;
  line-height: 1.45;
  font-variant-numeric: tabular-nums;
}
.learn-table th,
.learn-table td {
  padding: .62em .9em;
  text-align: left;
  vertical-align: top;
  border-bottom: 1px solid var(--cad-rule-2, #D9DFDE);
}
.learn-table thead th {
  background: var(--cad-stage-2, #D8DEDD);
  border-bottom: 1px solid var(--cad-rule, #C2CAC9);
  font-weight: 700;
  font-size: .88rem;
  letter-spacing: .02em;
  color: var(--cad-ink, #1B2225);
  vertical-align: bottom;
}
.learn-table tbody tr:nth-child(even) td { background: var(--cad-stage, #EEF1F0); }
.learn-table tbody tr:last-child td { border-bottom: 0; }
.learn-table .al-right { text-align: right; }
.learn-table .al-center { text-align: center; }
.learn-table td.is-pass { color: var(--cad-ok, #2C744A); font-weight: 600; }
.learn-table td.is-fail { color: var(--cad-danger, #A6362A); font-weight: 600; }
.learn-table td.is-warn { color: var(--cad-warn, #A34C14); font-weight: 600; }
.learn-table td.is-pass strong,
.learn-table td.is-fail strong,
.learn-table td.is-warn strong { color: inherit; }

/* Figures (inline SVG from figs/<slug>/fN.svg, or a raster img:) */
.learn-fig { margin: 1.9em 0 2em; }
.learn-fig > svg,
.learn-fig > img {
  display: block;
  width: 100%;
  height: auto;
  max-width: 100%;
  background: var(--fig-bg);
  border: 1px solid var(--cad-rule, #C2CAC9);
  border-radius: 4px;
}
.learn-fig > svg { color: var(--fig-ink); }
.learn-fig figcaption {
  margin-top: .65em;
  font-size: .9rem;
  line-height: 1.55;
  color: var(--cad-ink-2, #4D595D);
}
.learn-fig-num { font-weight: 700; color: var(--cad-ink, #1B2225); }
.learn-fig-missing .learn-fig-box {
  padding: 2.5em 1em;
  text-align: center;
  font-family: var(--font-mono, ui-monospace, Consolas, monospace);
  font-size: .9rem;
  color: var(--cad-warn, #A34C14);
  border: 2px dashed var(--cad-warn, #A34C14);
  border-radius: 4px;
  background: var(--cad-stage, #EEF1F0);
}

/* ── End of article: related-product box, general-information note ──── */
.learn-cta {
  margin: 2.6em 0 1.4em;
  padding: 1.2em 1.4em 1.25em;
  background: var(--cad-accent-soft, #D2E6EB);
  border: 1px solid var(--cad-rule, #C2CAC9);
  border-left: 4px solid var(--cad-accent, #0D6C87);
  border-radius: 0 4px 4px 0;
  font-size: 1rem;
  line-height: 1.7;
}
.learn-cta-label {
  display: block;
  margin: 0 0 .45em;
  font-size: .74rem; font-weight: 700; letter-spacing: .09em; text-transform: uppercase;
  color: var(--cad-accent, #0D6C87);
}
.learn-cta p { margin: 0 0 .8em; }
.learn-cta p:last-child { margin-bottom: 0; }

.learn-note {
  display: flex; gap: .65em; align-items: flex-start;
  margin: 0 0 .5em;
  padding: .8em 1em;
  font-size: .9rem; line-height: 1.6;
  color: var(--cad-ink-2, #4D595D);
  background: var(--cad-stage, #EEF1F0);
  border: 1px solid var(--cad-rule-2, #D9DFDE);
  border-radius: 4px;
}
.learn-note::before {
  content: "i";
  flex: none;
  display: inline-grid; place-items: center;
  width: 1.35em; height: 1.35em; margin-top: .12em;
  border-radius: 50%;
  border: 1.5px solid var(--cad-ink-2, #4D595D);
  font: 700 .8em/1 Georgia, "Times New Roman", serif;
  font-style: italic;
}
.learn-note em { font-style: normal; }

/* ── Author box ─────────────────────────────────────────────────────── */
.learn-author {
  display: flex; gap: 1rem; align-items: flex-start;
  margin: 2rem 0 0;
  padding: 1.2rem 1.35rem;
  background: var(--cad-stage, #EEF1F0);
  border: 1px solid var(--cad-rule, #C2CAC9);
  border-radius: 4px;
}
.learn-author-badge {
  flex: none;
  display: grid; place-items: center;
  width: 52px; height: 52px; border-radius: 50%;
  background: var(--cad-accent, #0D6C87);
  color: var(--cad-accent-ink, #fff);
  font-family: var(--font-display, "Barlow Condensed", sans-serif);
  font-size: 1.25rem; font-weight: 700; letter-spacing: .02em;
}
.learn-author-text { min-width: 0; }
.learn-author-label {
  margin: 0;
  font-size: .72rem; font-weight: 700; letter-spacing: .09em; text-transform: uppercase;
  color: var(--cad-ink-2, #4D595D);
}
.learn-author-name {
  margin: .1rem 0 0;
  font-family: var(--font-display, "Barlow Condensed", sans-serif);
  font-size: 1.3rem; font-weight: 700; line-height: 1.25;
  color: var(--cad-ink, #1B2225);
}
.learn-author-name a { color: inherit; }
.learn-author-name a:hover { color: var(--cad-accent, #0D6C87); }
.learn-author-title { margin: .1rem 0 0; font-size: .95rem; color: var(--cad-ink-2, #4D595D); }
.learn-author-bio { margin: .5rem 0 0; font-size: .95rem; line-height: 1.6; }
.learn-author-more { margin: .55rem 0 0; font-size: .9rem; }
.learn-author-more a { color: var(--cad-accent, #0D6C87); text-decoration: underline; text-underline-offset: 3px; }

/* author.json still has [[...]] placeholders: make it impossible to miss */
.learn-author.is-placeholder {
  border: 2px dashed var(--cad-warn, #A34C14);
  background: repeating-linear-gradient(135deg,
    transparent 0 14px, rgba(163, 76, 20, .06) 14px 28px), var(--cad-stage, #EEF1F0);
}
.learn-author.is-placeholder .learn-author-badge { background: var(--cad-warn, #A34C14); }
.learn-placeholder-flag {
  display: inline-block;
  margin: 0 0 .4rem;
  padding: .15rem .5rem;
  font-family: var(--font-mono, ui-monospace, Consolas, monospace);
  font-size: .72rem; font-weight: 700; letter-spacing: .06em;
  color: var(--cad-warn, #A34C14);
  border: 1.5px dashed var(--cad-warn, #A34C14);
  border-radius: 3px;
}

/* ── /learn/ index ──────────────────────────────────────────────────── */
.learn-index-head { margin: 0 0 1.6rem; }
.learn-intro {
  margin: .2rem 0 0;
  max-width: 64ch;
  font-size: 1.08rem; line-height: 1.7;
  color: var(--cad-ink-2, #4D595D);
}
.learn-cards {
  list-style: none; margin: 0; padding: 0;
  display: grid; gap: 14px;
}
.learn-card {
  position: relative;
  padding: 1.25rem 1.45rem 1.15rem;
  background: var(--cad-panel, #F5F7F6);
  border: 1px solid var(--cad-rule, #C2CAC9);
  border-left: 4px solid var(--cad-rule, #C2CAC9);
  border-radius: 4px;
  transition: border-color .2s ease;
}
.learn-card:hover,
.learn-card:focus-within { border-color: var(--cad-accent, #0D6C87); }
.learn-card h2 {
  margin: 0 0 .45rem;
  font-family: var(--font-display, "Barlow Condensed", sans-serif);
  font-size: 1.4rem; font-weight: 700; line-height: 1.2;
  color: var(--cad-ink, #1B2225);
}
.learn-card h2 a { color: inherit; }
.learn-card h2 a::after { content: ""; position: absolute; inset: 0; }
.learn-card h2 a:focus-visible { outline: none; }
.learn-card:focus-within { outline: 2px solid var(--cad-accent, #0D6C87); outline-offset: 2px; }
.learn-card:hover h2 { color: var(--cad-accent, #0D6C87); }
.learn-card p {
  margin: 0 0 .7rem;
  font-size: .98rem; line-height: 1.6;
  color: var(--cad-ink-2, #4D595D);
}
.learn-card-meta {
  display: flex; flex-wrap: wrap; gap: .2rem .6rem; align-items: baseline;
  font-size: .84rem; color: var(--cad-ink-2, #4D595D);
}
.learn-card-more { color: var(--cad-accent, #0D6C87); font-weight: 600; }
.learn-index-note { margin-top: 1.6rem; }

/* ── Phones ─────────────────────────────────────────────────────────── */
@media (max-width: 768px) {
  /* style.css slides the closed phone menu up by 110% of its own height; a short menu then still
     covers the top of the bar (and the logo). Hide it fully while closed, after the slide-up. */
  .learn-page .nav-menu { visibility: hidden; transition: transform var(--t-slow, 400ms ease), visibility 0s linear .4s; }
  .learn-page .nav-menu.open { visibility: visible; transition: transform var(--t-slow, 400ms ease), visibility 0s; }
  .learn-main { padding-top: calc(var(--nav-h, 64px) + env(safe-area-inset-top, 0px) + 18px); padding-bottom: 56px; }
  .learn-sheet { padding: 28px 24px 32px; }
}
@media (max-width: 600px) {
  .learn-wrap { padding: 0; }
  .learn-breadcrumb { padding: 0 16px; }
  .learn-index-head { padding: 0 16px; }
  .learn-sheet {
    border-left: 0; border-right: 0; border-radius: 0;
    padding: 22px 16px 28px;
  }
  .learn-body { font-size: 1rem; line-height: 1.72; }
  .learn-body h2 { font-size: 1.42rem; margin-top: 2em; }
  .learn-body h3 { font-size: 1.12rem; }
  .learn-body blockquote { font-size: .86rem; padding: .75em .85em; margin-left: 0; margin-right: 0; }
  .learn-table table { font-size: .9rem; }
  .learn-table th, .learn-table td { padding: .55em .7em; }
  .learn-table.cols-4 table { min-width: 540px; }
  .learn-table.cols-5 table,
  .learn-table.cols-6 table { min-width: 640px; }
  .learn-cta { padding: 1em 1.05em 1.05em; }
  .learn-author { padding: 1rem; gap: .8rem; }
  .learn-author-badge { width: 44px; height: 44px; font-size: 1.1rem; }
  .learn-cards { gap: 10px; padding: 0 0; }
  .learn-card { border-left-width: 4px; border-right: 0; border-radius: 0; padding: 1.05rem 16px 1rem; }
  .learn-card h2 { font-size: 1.28rem; }
  .learn-index-note { margin: 1.4rem 16px 0; }
}

@media print {
  .navbar, .footer, .learn-skip, #rhces-theme-toggle { display: none !important; }
  .learn-main { padding-top: 0; background: #fff; }
  .learn-sheet { border: 0; padding: 0; }
}

/* Phones: keep figure labels readable. The drawing keeps a minimum width and scrolls sideways inside its own box. */
@media (max-width: 640px) {
  .learn-fig { overflow-x: auto; -webkit-overflow-scrolling: touch; }
  .learn-fig > svg, .learn-fig > img { min-width: 600px; max-width: none; width: 600px; }
  .learn-fig figcaption { position: sticky; left: 0; width: calc(100vw - 32px); max-width: 100%; }
  .learn-fig figcaption::before { content: "Swipe the figure sideways to see all of it. "; font-style: italic; opacity: .75; }
}